In the German national annex of Eurocode 8 (EC8) "Design of structures for earthquake resistance", the influence of local ground conditions on earthquake impact has to be taken into account. Generally, the shallow structure is classified as a combination of one of three geological subsurface classes and one of three subsoil classes in the national annex. For the determination of the subsoil class, the rock mass down to a depth of 30 meters is considered. For the determination of the geological subsurface class, the structure below 30 m depth down to several hundred meters is considered.

As part of the recent update of the national annex of EC8, the map of geological subsurface classes, which is a part of the code, was revised. For the new map, the methods of geological 3D modelling were used for the first time. Based on data from the geological 3D models of the federal states Baden-Württemberg, Bavaria, Hesse, North Rhine-Westphalia, Rhineland-Palatinate, Saxony, Saxony-Anhalt, and Thuringia, the thicknesses of Quaternary and Tertiary sediments were determined first. Based on these thicknesses, the geological subsurface classes "R" (rock), "T" (shallow sediment basins), and "S" (deep sediment basins of more than 100 m thickness) were assigned. The geological subsurface classes were presented on a grid with a cell size of 1 km x 1 km. Compared to the previous assignation of geological subsurface classes, in which geological structures of less than 20 km extension or diameter could not be considered, a significantly higher spatial resolution was achieved.

Semi-automatically generated maps highlight the variability of the stratigraphic thickness of the Helvetic Kieselkalk. This geological unit is exposed in different Helvetic nappes over more than 300 km along the Swiss Alps and it is commonly extracted to produce hard rock aggregates for the national road and railway infrastructure. The deposition of this unit onto the European (Helvetic) continental margin during the Early Cretaceous coincided with normal faulting, which lead to strong lateral thickness variations.

The Python and MATLAB approach used to create the thickness maps was developed as part of a Switzerland-wide mineral resource mapping project and has been applied to the geological vector dataset GeoCover. The approach is designed to rapidly generate large-scale map overviews of the stratigraphic thickness, for which the construction of 3D models would be very time consuming.

Our results highlight an increase in thickness along the Alps from 100 m in the west to 1000 m in the east. The depositional thickness was certainly modified by the subsequent burial, folding, and faulting during the formation of the Helvetic nappes. Two discrete thickness jumps indicate the presence of three sedimentary basins in east-west direction with a half-graben-like geometry. These thickness jumps coincide with present-day nappe boundaries and suggests that the inherited basin geometry influenced the nappe formation.

The large-scale thickness maps and the improved undestanding of the paleogeography and tectonic evolution are used to rapidly identify mineral occurrences with favourable geometry. These can, when sufficiently investigated, be considered in land use or resource safeguarding plans.

Structural geologic modeling and subsurface process simulation are important tools in geoscience. Various software solutions—ranging from manual to semi-automated—are available in this field. These include proprietary and open-source software, often covering specific components of a larger workflow. Consequently, comprehensive workflows typically combine different software solutions and custom-built tools to address specific scenarios.

However, these workflows frequently require substantial manual adjustments and are tailored to particular applications, making reuse challenging without significant modifications by skilled professionals. In addition, it is not always possible to access all parts of a workflow, reducing transparency and the flexibility to modify components.

To address this issue, within the project WBGeo, supported by BMBF through the programme “Geoforschung für Nachhaltigkeit (GEO:N), Digitale Geosysteme: Virtuelle Methoden und digitale Werkzeuge für geowissenschaftliche Anwendungen”, we aim to develop a workbench for digital geosystems. This workbench enables the creation of complete workflows by integrating three core components: structural geologic modeling, numeric process simulation, and visualization as well as the interfaces between these components. A visual scripting environment using an underlying domain-specific language provides intuitive access for users with limited technical expertise. At the same time, the flexible modular structure ensures that experienced users have full access to the underlying code, allowing them to customize existing or add new components as needed.
This structure increases reproducibility, transparency, accessibility and comparability of workflows, as a multitude of components are available in a single framework.